let str = 'hello'
let s = 'world'
let num = 123
// 变量和字符串的拼接用+连接
// let res = str + s + 'I am jerry'
// 也可以用`${}`来读取
let res = `${str} ${s} I am jerry`
console.log(res)

let reg = /^1[3-9]\d{9}$/
console.log(reg.test('18779679773'))